If you take the 3.1415 and divide by 4 you get the 0.785375
OR if you take the four 1" outlets at 0.785375 and times them by 4 the you get 3.1415....so my point being 4 outlets at 1" diameter is the exact same size as one inlet of 2"....

I deserved the jabs...

I do still agree that the flow based on TUNED flow could be the issue...but it is not a bad place to start.